Beds of Tertiary age in the Gulf Coast of Texas and Louisiana constitute one of the most prolific producing oil provinces in the world, yet there is little regional folding and an absence of large tectonic movements, and therefore no major structural features of great relief which characterize many other oil-producing provinces. The Gulf Coast was, and still is, an area of low relief, both inside and beyond the coast line, with deposits through the Tertiary made up principally of continental beds and of sediments deposited in shallow marine waters, with a series of regressions and transgressions, with the net effect of moving the shore line toward the south. During these oscillations there occurred erosional periods and consequent minor, but effective, truncation of beds and traps for accumulation of oil and gas.

Despite the absence of structures of great relief, accumulations of hydrocarbons are present in the Gulf Coast with less intense features of every known type: anticlines, faults, faulted anticlines, sand lenses, stratigraphic traps of all types, reefs, and a combination of these structural and stratigraphic forms.

The general progressive and thick deposition during the Tertiary in this large Gulf Coast homocline, amounting to a total of 50,000 feet, has resulted in certain structural features, among which the most outstanding are the salt domes. The motive force of the uplift of these domes has been the static weight of the thick Tertiary sediments, so that the great vertical growth of the domes has taken place during the Tertiary.

The various types of hydrocarbon accumulations have been proved by drilling on the Gulf Coast salt domes, and one of these, the South Liberty salt dome, in Liberty County, Texas, 45 miles east of Houston, is the subject of this paper, because it exemplifies the economic importance of various types of oil traps which were formed at several stages in the growth of the dome. This field is now being extensively and successfully explored for additional producing zones.

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